Questions about riders and odd requests - any insiders here?

When artists require unusual items in their rider (specialized non-perishable foods, personal products, or other miscellany), do they scoop the leftovers up and take them post-show, or leave them behind?

If artists take them, wouldn't they end up with a ridiculous amount by the end of the tour? Such that they could comfortably strike them from the rider at later venues altogether?

If artists leave them, what does the venue do with the stuff, assuming they're not part of the usual catering/supplies inventory?